Method and system of preconditioning transmitted signals

ABSTRACT

A communication system transmits data signals between communication nodes. A first data signal is transmitted as an electromagnetic wave along a first data transmission path to a receiver using skywave propagation. A second data signal, identical to the first data signal, is transmitted to the receiver along a second data transmission path. The two data signals are compared at the receiver to determine any distortion caused by the skywave propagation. Data regarding the distortion is sent back to the transmitter so that subsequent transmitted data signals may be preconditioned when sent by skywave propagation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/929,248, filed Apr. 2, 2020, which is hereby incorporated byreference. U.S. patent application Ser. No. 15/929,248, filed Apr. 2,2020, is a continuation of International Patent Application NumberPCT/US2018/053949, filed Oct. 2, 2018, which are hereby incorporated byreference. International Patent Application Number PCT/US2018/053949,filed Oct. 2, 2018, claims the benefit of U.S. Patent Application No.62/567,444, filed Oct. 3, 2017, which are hereby incorporated byreference.

BACKGROUND

Skywave propagation may be an effective communication method forproviding low-latency data transmission between a transmitter and areceiver that are separated by a large distance. Although skywavepropagation may reduce transmission times compared to other methods ofcommunication such as fiber optic cables and satellite networks,distortion caused by ionospheric and other atmospheric conditions maycause a delay in processing the data signal as the data signal isunscrambled. In some instances, these delays may prove to be costly. Forexample, orders to buy and sell securities or other financialinstruments in world markets, or even news pertinent to tradingstrategies, typically rely on communications links that carry data andinstructions and delays of even a few milliseconds can cost millions ofdollars. Therefore, it may be beneficial to have a communication systemthat that can reduce the effect of distortion caused by ionosphericconditions on skywave propagation.

SUMMARY

Skywave propagation may be used to provide a low-latency communicationpathway for data between remotely located transmitter and receiverstations. Ionospheric and other atmospheric conditions may causedistortion of a data signal transmitted by skywave propagation.Generally speaking, monitoring ionospheric and other environmentalconditions may allow a transmitter to change or precondition a datasignal to the current conditions such that the current atmosphericconditions effectively unscramble or remove noise from thepreconditioned signal when received at the receiver station. The overallsystem is designed to minimize latency as well as reduce noise of thesignal. In this system, a fiber back channel provides a copy of the datasignal transmitted via skywave propagation. At a receiver station, thedata is decoded. Based on the copy of the signal originally receivedfrom the fiber channel, the receiver station can determine whatdistortions occurred in the atmosphere as it unscrambles the signalstransmitted via skywave propagation. Once it receives these parameters,it transmits some or all of this information back to the transmitterstation via the fiber channel and/or via skywave propagation. Thetransmitter station then preconditions one or more of the next signalsthat are transmitted via skywave propagation.

Preconditioning reduces any type of downstream processing time requiredto unscramble or remove noise from the signal. In other words, theenvironmental conditions are in essence performing some or all of thedescrambling so as to reduce processing time at the receiver. In onevariation, the system can precondition multiple variations of signals tobe transmitted. These items can correspond to a particular tradingstrategy that is used and/or news impacting the trading strategy. Thetrader can then pick an item from the list to be transmitted and theparticular information signal can then be immediately transmitted viaskywave propagation.

While the system will be described with reference to executing financialtrading strategies, this system and technique can be used in othersituations or industries where time and bandwidth are of concern. Forexample, this system can be used to perform remote surgery or medicaldiagnostics, scientific instruments or studies (e.g., for astronomy orphysics), controlling dispersed global computer networks, and/ormilitary applications. This system and technique can for example beadapted for incorporation into earthquake/tsunami early warning systems.Certain remote deep water earthquake sensor may provide a signal toinstitute a complicated cascade of actions to protect designatedpopulation centers and associated infrastructure depending on theseverity and type of earthquake. For instance, upon detecting anearthquake (or resulting tsunami), a sensor or monitoring center cantransmit a signal that causes nuclear reactors to immediately scramand/or the power grid to reroute power to emergency infrastructure toalleviate the situation. In another example, the technique can be usedfor underlying maintenance or enhancements to the communication systemitself. By way of a non-limiting example, since the files are typicallylarge, code for programming and/or reprograming the modems, antennas,and/or other equipment at the receiver station (or transmitter station)can be sent along a high bandwidth, high latency link, such as a fiberoptic cable. Alternatively or additionally, some or all of the code canbe sent via skywave propagation (e.g., radio), and/or via line of sitetransmission, such as via microwaves. The code can includes one or moreprograms, libraries, data, and/or subroutines for controlling theequipment depending on various circumstances. The transmitter stationvia skywave propagation can send a triggering signal to the receiver soas to select all or part of the code to execute so as to modify orreprogram the equipment at the receiver station. For instance, the codecan be used to tune the receiver station for particular characteristics,such as for reducing latency, power consumption, and/or error (and/orincreasing bandwidth). These tuning characteristics can includetradeoffs that do not work well under certain operational conditions,times, and/or environmental characteristics. One subroutine in the codefor example can be optimized for latency reduction, another for errorreduction, and still yet another for conserving power. The triggeringsignal in this example can be used to select one of these subroutines soas to reprogram the receiver depending on the needs at that particulartime. The resulting changes can be software changes that change thefunction of the equipment and/or physical changes to the equipment, suchas to the height and/or angle of the antenna system. Later on, dependingon the needs at that time, different subroutines, programs, data, and/orareas of the code can be selected via the triggering signal. Updates orchanges to the code can be sent periodically, continuously, or on an asneeded basis.

Some changes or distortions along the skywave propagation path arepredictable and/or occur at such a slow rate so as to make them suitablefor this preconditioning technique so as to for example reduce overallcommunication latency, reduce errors, and/or free up bandwidth. It wasdiscovered for example that the environmental changes for Dopplershifting (or drift over time) along the skywave path, which changes thefrequency of the received triggering signal, can occur at a slow enoughpace so as to make it suitable for preconditioning. A full or partialinverse factor of this Doppler shift in one variation is applied to thetriggering signal before or during transmission. As an example, when theDoppler shift along the skywave path reduces the frequency of thetriggering signal, the receiver station reports this lower frequencyand/or frequency change back to the transmitter station along the fiberback channel and/or skywave path (or some other communication link).Based on the reported change of frequency, the transmitter for some orall subsequent transmissions increases the frequency of the triggeringsignal by a factor corresponding to or around this Doppler shiftfrequency change. As a result of this frequency increase of thetransmitted triggering signal, the received triggering signal willlikely reduce or even cancel out the Doppler shifting which in turnpotentially reduces signal processing time and/or errors. Other signalcharacteristics, such as amplitude, polarization, and/or phase, can beused for preconditioning the signal. For instance, an inverse functionof a detected noise signal that can include frequency, amplitude,polarization, and/or phase distortion components can be applied so as toprecondition any subsequently transmitted triggering signals.

As might be appreciated, preconditioning may not be perfect. In oneexample, the receiver station progresses through or runs parallel light,medium, and heavy decoding of the signal in cases where thepreconditioning does not provide adequate descrambling. The lightdecoding method typically, but not always, has the quickest processingtime so that the information can be transmitted more quickly. In oneparticular example, the receiver system progresses through the light,medium, and heavy decoding methods and once a particular signal has beendecoded, it stops at the one that has the shortest processing time thatis able to unscramble the signal. As discussed, this processing can goin parallel as well. Once the information from the data signals getsunscrambled, the data is transmitted further on for further use, such asto a financial institution for financial trading.

Further forms, objects, features, aspects, benefits, advantages, andembodiments of the present invention will become apparent from adetailed description and drawings provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a system for transmitting data overseparate communication links, one of which uses skywave propagation.

FIG. 2 is a schematic diagram further illustrating the skywavepropagation of FIG. 1

FIG. 3 is a schematic diagram illustrating the use of ground-basedrepeaters in the skywave propagation of FIG. 1.

FIG. 4 is a schematic diagram illustrating the use of airborne repeatersin the skywave propagation of FIG. 1.

FIG. 5 is a schematic diagram illustrating additional layers of theatmosphere including the ionized layer shown in FIG. 1.

FIG. 6 is a schematic diagram illustrating various ionized layers of theatmosphere shown in FIG. 5.

FIG. 7 is a schematic diagram illustrating additional details of skywavepropagation generally illustrated in FIGS. 1-6.

FIG. 8 is a schematic diagram illustrating additional detail for thecommunication nodes of FIG. 1.

FIG. 9 is a schematic diagram illustrating additional detail for the RFcommunication interface in FIG. 8.

FIG. 10 is a flowchart illustrating a method for preconditioning a datasignal.

FIG. 11 is a schematic diagram further illustrating a system fortransmitting data over separate communication links.

FIG. 12 is a schematic diagram illustrating distortion caused by skywavepropagation.

FIG. 13 is a schematic diagram illustrating sending a preconditioneddata signal by skywave propagation.

FIG. 14 is a flowchart illustrating a method of decoding a data signal.

FIG. 15 is a flowchart illustrating a method of decoding and processinga data signal.

DESCRIPTION OF THE SELECTED EMBODIMENTS

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates. One embodiment of the invention is shown in great detail,although it will be apparent to those skilled in the relevant art thatsome features that are not relevant to the present invention may not beshown for the sake of clarity.

FIG. 1 illustrates at 100 one example of a system configured to transferdata via a low latency, low bandwidth communication link 104, andseparate data via a high latency, high bandwidth communication link 108.The communication links 104 and 108 provide separate connections betweena first communication node 112 and a second communication node 116. Thelow latency communication link 104 may be configured to transmit datausing electromagnetic waves 124 passing through free space via skywavepropagation. The electromagnetic waves 124 may be generated by atransmitter in the first communication node 112 and passed along atransmission line 136 to an antenna 128. The electromagnetic waves 124may be radiated by the antenna 128 encountering an ionized portion ofthe atmosphere 120. This radiated electromagnetic energy may then berefracted by the ionized portion of the atmosphere 120 causing the waves124 to redirect toward earth. The waves 124 may be received by areceiving antenna 132 coupled to the second communications node 116 bythe transmission line 140. As illustrated in FIG. 1, a transmittingcommunication node may use skywave propagation to transmitelectromagnetic energy long distances across the earth surface withoutthe need of one or more transmission lines to carry the electromagneticenergy.

Data may also be transmitted between the communications nodes 112 and116 using a high latency communication link 108. As illustrated in FIG.1, the high latency communication link 108 may be implemented using atransmission line 144 passing through the earth, which may includepassing under or through an ocean or other body of water. As shown inFIG. 1, the high latency communication link 108 may include repeaters152. FIG. 1 illustrates four repeaters 152 along the transmission line144 although any suitable number of repeaters 152 may be used. Thetransmission line 144 may also have no repeaters at all. Although FIG. 1illustrates the communication link 104 transmitting information from thefirst communication node 112 to the second communication node 116, thedata transmitted may pass along the communication links 104, 108 in bothdirections.

A client 160 may have a connection 164 to the first communication node112. The client 160 may send instructions over the connection 164 to thefirst communication node 112. At the first communication node 112, theinstructions are prepared to be sent to the second communication node116, either by the low latency link 104 or the high latency link 108, orboth. The second communication node 116 may be connected to aninstruction processor 168 by a connection 172. The client 160 may be anybusiness, group, individual, or entity that desires to send directionsover a distance. The instruction processor 168 may be any business,group, individual, or entity that is meant to receive or act upon thoseinstructions. In some embodiments, the connections 164 and 172 may beunnecessary as the client may send the data to be transmitted directlyfrom the communication node 112 or the communication node 116 may beconnected directly to the instruction processor 168. The system 100 maybe used for any kind of low-latency data transmission that is desired.As one example, the client 160 may be a doctor or surgeon workingremotely while the instruction processor 168 may be a robotic instrumentfor working on a patient.

In some embodiments, the client 160 may be a financial instrument traderand the instruction processor 168 may be a stock exchange. The tradermay wish to provide instructions to the stock exchange to buy or sellcertain securities or bonds at specific times. In other variations,instead of specific instructions from the trader, the transmittedinformation or instructions may alternatively or additionally includenews information, such as news about a particular company, industry,governmental agency, exchange, weather, politics, and/or otherinformation that may impact the trading strategy. The trader maytransmit the instructions to the first communication node 112 whichsends the instructions to second communication node using the antennae128, 132 or by the transmission line 144. The stock exchange can thenprocess the actions desired by the trader upon receipt of theinstructions.

The system 100 may be useful for high-frequency trading, where tradingstrategies are carried out on computers to execute trades in fractionsof a second. In high-frequency trading, a delay of mere milliseconds maycost a trader millions of dollars; therefore, the speed of transmissionof trading instructions is as important as the accuracy of the datatransmitted. In some embodiments, the trader may transmit preset tradinginstructions or conditions for executing a trade to the communicationnode 116, which is located within close proximity to a stock exchange,using the high latency, high bandwidth communication link 108 at a timebefore the trader wishes to execute a trade. These instructions orconditions may require the transmission of a large amount of data, andmay be delivered more accurately using the higher bandwidthcommunication link 108. Also, if the instructions or conditions are sentat a time prior to when a trade is wished to be executed, the higherlatency of the communication link 108 can be tolerated.

The eventual execution of the instructions may be accomplished by thetrader transmitting triggering data to the system on which theinstructions are stored. Upon receipt of the triggering data, thetrading instructions are sent to the stock exchange and a trade isexecuted. The triggering data that is transmitted is generally a muchsmaller amount of data than the instructions; therefore, the triggeringdata may be sent over the low latency, low bandwidth communication link104. When the triggering data is received at communication node 116, theinstructions for (and/or news associated with) a specific trade are sentto the stock exchange. Sending the triggering data over the low latencycommunication link 104 rather than the high latency communication link108 allows the desired trade to be executed as quickly as possible,giving the trader a time advantage over other parties trading the samefinancial instruments.

The configuration shown in FIG. 1 is further illustrated in FIG. 2 wherethe first communication node 112 and the second communication node 116are geographically remote from one another separated by a substantialportion of the surface of the earth (156). This portion of the earth'ssurface may include one or more continents, oceans, mountain ranges, orother geographic areas. For example, the distance spanned in FIGS. 1-7may cover a single continent, multiple continents, an ocean, and thelike. In one example, the first communication node 112 is in Chicago,Ill. in the United States of America, and the second communication node116 is in London, England, in the United Kingdom. In another example,the first communication node 112 is in New York City, N.Y., and secondcommunication node 116 is in Los Angeles, Calif., both cities being inNorth America. Any suitable combination of distance, communicationnodes, and communications links is envisioned that can providesatisfactory latency and bandwidth.

FIG. 2 illustrates that skywave propagation allows electromagneticenergy to traverse long distances. Using skywave propagation, the lowlatency communication link 104 transmits the electromagnetic waves 124into a portion of the atmosphere 120 that is sufficiently ionized torefract the electromagnetic waves 124 toward the earth. The waves maythen be reflected by the surface of the earth and returned to theionized portion of the upper atmosphere 120 where they may be refractedtoward earth again. Thus electromagnetic energy may “skip” repeatedlyallowing the low latency, low bandwidth signals 124 to cover distancessubstantially greater than those which may be covered by non-skywavepropagation.

Another example of the system illustrated in FIG. 1 appears in FIG. 3where the skywave propagation discussed with respect to FIGS. 1 and 2may be enhanced using repeaters 302 and 306. In this example, the firstrepeater 302 may receive the low latency communication signals emanatingfrom the antenna 128. The signals may be refracted by the ionized region120 and returned to earth where they may be received by the repeater 302and retransmitted via skywave propagation. The refracted signal may bereceived by the repeater 306 and retransmitted using skywave propagationto the second communications node 116 via the antenna 132. Although tworepeating stations are illustrated in FIG. 3, any suitable number,configuration, or positioning of the ground repeating stations 302 isconsidered. Increasing the number of repeaters 302, 306 may provide forthe opportunity to transmit low latency signals over greater distancesin a wider array of atmospheric missions, however, the physicallimitations of the repeater circuitry that receives and retransmits thesignal may add additional latency to low latency communication link 104.

FIG. 4 illustrates another example of the system illustrated in FIG. 1where one or more repeaters along the first communications link areairborne, such as in an aircraft, dirigible, balloon, or other device410 configured to maintain the repeater aloft in the atmosphere. In thisexample, signals transmitted from the first communications node 112 viathe antenna 128 may be received by an airborne repeater 414 either asline of sight communication 402, or by skywave propagation as describedherein elsewhere. The signals may be received by the airborne repeater414 and retransmitted as line of sight communication 406, or by skywavepropagation to the second communications node 116 along the low latencylink 104.

Additional details regarding skywave propagation are illustrated inFIGS. 5-7. The relation to the system disclosed and various layers ofthe upper atmosphere is illustrated in FIG. 5. For purposes of radiotransmission, the layers of the upper atmosphere may be divided as showninto successively higher layers such as the troposphere 504, thestratosphere 508, and the ionosphere 512.

The ionosphere is named as such because it includes a high concentrationof ionized particles. The density of these particles in the ionospherefurthest from earth is very low and becomes progressively higher in theareas of the ionosphere closer to earth. The upper region of theionosphere is energized by powerful electromagnetic radiation from thesun which includes high-energy ultraviolet radiation. This solarradiation causes ionization of the air into free electrons, positiveions, and negative ions. Even though the density of the air molecules inthe upper ionosphere is low, the radiation particles from space are ofsuch high energy that they cause extensive ionization of the relativelyfew air molecules that are present. The ionization extends down throughthe ionosphere with diminishing intensity as air becomes denser with thehighest degree of ionization thus occurring at the upper extremities ofthe ionosphere, while the lowest degree occurs in the lower portion ofthe ionosphere.

These differences in ionization between the upper and lower extremitiesof the ionosphere 512 are further illustrated in FIG. 6. The ionosphereis illustrated in FIG. 6 with three layers designated, respectively,from lowest level to highest level as D layer 608, E layer 612, and Flayer 604. The F layer 604 may be further divided into two layersdesignated F1 (the higher layer) at 616 and F2 (the lower layer) at 620.The presence or absence of layers 616 and 620 in the ionosphere andtheir height above the earth vary with the position of the sun. At highnoon, radiation from the sun 624 passing into the ionosphere isgreatest, tapering off at sunset and at a minimum at night. When theradiation is removed, many of the ions recombine causing the D layer 608and the E layer 612 to disappear, and further causing the F1 and F2layers 616, 620 to recombine into a single F layer 604 during the night.Since the position of the sun varies with respect to a given point onearth, the exact characteristics of the layers 608, 612, 616, and 620 ofthe ionosphere 512 can be extremely difficult to predict but may bedetermined by experimentation.

The ability for a radio wave to reach a remote location using skywavepropagation depends on various factors such as ion density in the layers608-620 (when they are present), the frequency of the transmittedelectromagnetic energy, and the angle of transmission. For example, ifthe frequency of a radio wave is gradually increased, a point will bereached where the wave cannot be refracted by the D layer 608 which isthe least ionized layer of the ionosphere 512. The wave may continuethrough the D layer 608 and into the E layer 612 where its frequency maystill be too great to refract the singles passing through this layer aswell. The waves 124 may continue to the F2 layer 620 and possibly intothe F1 layer 616 as well before they are bent toward earth. In somecases, the frequency may be above a critical frequency making itimpossible for any refraction to occur causing the electromagneticenergy to be radiated out of the earth's atmosphere (708).

Thus, above a certain frequency, electromagnetic energy transmittedvertically continues into space and is not refracted by the ionosphere512. However, some waves below the critical frequency may be refractedif the angle of propagation 704 is lowered from the vertical. Loweringthe angle of propagation 704 also allows the electromagnetic waves 124transmitted by the antenna 128 to be refracted toward Earth's surfacewithin a skip zone 720 making it possible to traverse a skip distance724 and reach a remote antenna 132. Thus the opportunity for successfulskywave propagation over a certain skip distance 724 is furtherdependent on the angle of transmission as well as the frequency, andtherefore the maximum usable frequency varies with the condition of theionosphere, desired skip distance 724, and the propagation angle 704.FIG. 7 also illustrates that non-skywave propagation such as groundwavesignals and/or line of sight signals 716 are unlikely to traverse theskip distance 724.

FIG. 8 illustrates one example of additional aspects of a communicationnode 800 which is like the communication nodes 112 and 116. Thecommunication node 800 can include a processor 804 for controllingvarious aspects of communication node 800. The processor may be coupledto a memory 816 useful for storing rules, command data 820, historicaltransmission data 822, and/or a transmission frequency model 860.Devices for accepting user input and providing output (I/O) to a user824 may also be included. These devices may include a keyboard orkeypad, a mouse, a display such as a flat panel monitor and the like, aprinter, plotter, or 3D printer, a camera, or a microphone. Any suitabledevices for user I/O may be included. Node 800 may also include anetwork interface 832 responsive to the processor 804 and coupled to acommunication network 836. A security module 828 may be included as welland may be used to reduce or eliminate the opportunity for third-partiesto intercept, jam, or change data as it passes between thecommunications nodes 800. In one example, the communication node 800 isimplemented as a computer executing software to control the interactionof the various aspects of the node 800.

The network interface 836 may be configured to send and receive datasuch as command data 820, or triggering data which may be passed from atriggering system 840. The communication network 836 may be coupled to anetwork such as the internet and configured to send and receive datawithout the use of skywave propagation. For example, the communicationnetwork 836 may transmit and receive data over optical fibers or othertransmission lines running along the earth similar to the transmissionlines 144 illustrated in previous figures.

The node 800 may include a second network interface 808 responsive tothe processor 804 and coupled to a radio-frequency communicationinterface 812. This second network interface 808 may be used to transferdata such as command data 820 or triggering data passed from thetriggering system 840. The network interface 808 may be coupled to anantenna like antenna 128 which may include multiple antennas or antennaelements. The radio-frequency communication interface 808 may beconfigured to send and receive data such as triggering data usingelectromagnetic waves transmitted and/or received via the antenna 128.As discussed above, the antenna 128 may be configured to send andreceive the electromagnetic waves via skywave propagation.

The communication node 800 may include additional aspects illustrated inFIG. 9. The radio-frequency communication interface 812 may include atransmitter 904 configured to transmit electromagnetic energy using theantenna 128. A receiver 908 may optionally be included as well andconfigured to receive electromagnetic waves from the antenna 128. Thetransmitter 904 and the receiver 908 may also be coupled to a modem 912configured to modulate signals received by the interface 812 to encodeinformation or data from a digital stream for transmission bytransmitter 904. The modem 912 may also be configured to demodulatesignals received by the receiver 908 from the antenna 128 to decode thetransmitted signal into a digital data stream usable by the processor804 or that may be stored in the memory 816.

Transmission by skywave propagation may cause distortion of thetransmitted data transmission due to ionospheric and atmosphericconditions. This distortion or the introduction of noise during skywavepropagation may cause the received signal to be inaccurate or couldincrease the latency time of data transmission as the receiver attemptsto unscramble the received data signal. If the distortion effects of theatmosphere are known, it may be possible to precondition a transmitteddata signal so that the distortion caused by the atmosphere effectivelygets rid of the added distortions and unscrambles and removes noise fromthe transmitted data signal. Therefore, when the data signal is receivedat the receiver, a substantially undistorted signal is received, savingtime in decoding the signal and providing a more accurate signal.

A method for preconditioning a data signal is shown in flowchart 1000,illustrated in FIG. 10. A first data signal 1104 (see FIG. 11) is sent1005 from a transmitter, such as the first communication node 112, to areceiver, such as the second communication node 116, by skywavepropagation. An example of a data transmission path for the first datasignal 1104 is the low-latency, low bandwidth communication link 104. Asecond data signal 1108 that is identical to the first data signal 1104is also sent 1010 from the transmitter to the receiver, but using adifferent data transmission path that does not use skywave propagation.One example of a possible data transmission path is the high-latency,high bandwidth communication link 108 that is formed by the transmissionline 144 extending between the first communication node 112 and thesecond communication node 116.

The first data signal 1104 and the second data signal 1108 are decoded1015 after they are received at the receiver. The decoded signals arecompared 1020 to determine any differences between the received firstdata signal 1104 and the received second data signal 1108. Because thefirst data signal 1104 and the second data signal 1108 were identical attransmission, any differences between the data signals at the receivermay indicate distortion caused in the first data signal due toionospheric or other atmospheric conditions during skywave propagation.These distortions caused by skywave propagation will not appear in thesecond data signal 1108 because the second data signal 1108 was sent bythe transmission line 144.

Data regarding the distortion of the first data signal 1104 is sent 1025back to the original transmitter. In some embodiments, the distortiondata may be sent back to the transmitter using the high-latency,high-bandwidth communication link 108, but in other embodiments, thedistortion data may be returned to the transmitter using skywavepropagation. After receiving the distortion data, the transmitter mayprecondition 1030 subsequent data signals to be transmitted by skywavepropagation based on the distortion data.

An example of how preconditioning may be used to reduce latency andimprove accuracy of a transmitted data signal is shown in FIGS. 12-13.In FIG. 12, a first transmitted data signal 1204 is sent betweencommunication nodes 112 and 116 using antennae 128, 132 by skywavepropagation. A second transmitted data signal 1208, identical to thefirst transmitted data signal 1204, is sent between the communicationnodes 112, 116 by the transmission line 144. The first transmitted datasignal 1204 is received at the communication node 116 as a firstreceived data signal 1214. The first received data signal 1214 hasexperienced distortion due to skywave propagation as several portions1222 of the received data signal 1214 are different than the transmitteddata signal 1204. Meanwhile, the second received data signal 1218 hasnot experienced the distortion that is seen in first received datasignal 1214 because it was not sent by skywave propagation.

The second communication node 116 may be compared to the first receiveddata signal 1214 and the second received data signal 1218 to determinewhere distortion has occurred. This distortion data may then be sentback to the first communication node 112 either by the transmission line144 or by skywave propagation from the antenna 132 to antenna 128. Afuture transmission of a transmitted data signal may then bepreconditioned so that distortions caused by the atmosphere in skywavepropagation modify the transmitted data signal so that it is changed tothe desired signal with minimum distortion or completely withoutdistortions.

FIG. 13 shows an example where a data signal identical to the firsttransmitted data signal 1204 is desired to be sent from the firstcommunication node 112 to the second communication node 116. As shown,the transmitted data signal 1304 is not the same as the desired firsttransmitted data signal 1204, but instead has already been distortedbased on the observed distortions found in the first received datasignal 1214. When the transmitted data signal 1304 is sent by skywavepropagation, the transmitted data signal 1304 is distorted by theatmosphere so that the preconditioned portions of transmitted datasignal 1304 are changed in a received data signal 1314 to correspondwith the desired data signal. Therefore, when the data signal 1314 isreceived at the second communication node 116, the data signal 1314includes only limited distortions or includes no distortions. Limitingdistortion of the received data signal 1314 reduces latency bydecreasing the processing time at the second communication node 116necessary for unscrambling or removing noise from the signal.

In some embodiments, preconditioning may not result in a completelyundistorted data signal received by the receiver and some additionaldistortion of the signal may still remain upon receipt of the signal.The flowchart 1400 shown in FIG. 14 illustrates a method of furtherdecoding a signal in which preconditioning does not provide adequatedescrambling. First, a preconditioned data signal that still containssome distortion after transmission is received 1405 at a receiver. Thereceiver performs 1410 a light decoding method to attempt to descramblethe distorted data signal. Generally, the light decoding method includesa form of decoding that is computationally inexpensive and has a shortprocessing time, allowing the data signal to be transmitted morequickly. If the data signal is able to be decoded 1415, then the datasignal is processed 1420 and any instructions or actions carried by thedata signal are executed.

If the data signal is not able to be descrambled by the light decoding,then a medium decoding process is performed 1425 on the received datasignal. The medium decoding process is generally a more intensivedecoding method than the light decoding method and typically takes alonger time to perform. If the medium decoding method is successful indescrambling the data signal 1430, then the data signal is processed1435 and any instructions or actions carried by the data signal areexecuted. If the data signal is not able to be descrambled by the mediumdecoding process, then heavy decoding is performed 1440 on the receiveddata signal. The heavy decoding method is the most computationallyexpensive of the decoding processes and generally takes longer than thelight or medium decoding processes to complete. Once the data signal hasbeen decoded by the heavy decoding process, the data signal is processed1445 and any instructions or actions carried by the data signal areexecuted.

An alternative method of decoding a preconditioned data signal that hasbeen transmitted by skywave propagation is shown in the flowchart 1500of FIG. 15. A preconditioned data signal that retains some distortionafter transmission is received 1505 at a receiver. A processor at thereceiver then attempts to decode the transmission by running threedifferent decoding programs in parallel. The processor performs 1510 alight decoding method while also performing 1515 a medium decodingmethod and performing 1520 a heavy decoding method. When the lightdecoding method is complete, the processor determines 1525 whether thismethod decoded the signal before the medium and heavy decoding methods.

If the light decoding method is completed first, then the data signalfrom the light decoding method is processed 1530 and any instructions oractions carried by the data signal are executed. This process isrepeated for each of the other decoding methods. When the mediumdecoding method is complete, the processor determines 1535 whether thismethod decoded the signal before the light and heavy decoding methods.If the medium decoding method is completed first, then the data signalfrom the medium decoding method is processed 1430 and any instructionsor actions carried by the data signal are executed. Likewise, when theheavy decoding method is complete, the processor determines 1545 whetherthis method decoded the signal before the light and medium decodingmethods. If the heavy decoding method is completed first, then the datasignal from the heavy decoding method is processed 1550 and anyinstructions or actions carried by the data signal are executed.

Typically, the light decoding method has the quickest processing time.However, in some instances, the light decoding method may not berigorous enough to decode the received data signal or somecharacteristics of the data signal may be more quickly decoded by eitherthe medium or heavy decoding methods despite the added computationalexpense. The parallel method of decoding the data signal shown in FIG.15 allows for the decoding method with the quickest processing time tobe used in order to decrease latency and to use the transmitted datasignal more quickly.

In some embodiments, preconditioning may be used in the transmission ofnews and/or financial trading instructions from a financial trader to astock exchange for high frequency trading. Because one of the mainconcerns in high-frequency trading is timing and submitting instructionsas quickly as possible, the reduced processing time and low-latency ofpreconditioned signals may afford advantages that could be worthmillions of dollars. In a certain embodiment, a financial trader maysubmit multiple variations of data signals containing tradinginstructions that are to be transmitted to a stock exchange. Thedifferent variations may correspond to a particular trading strategythat may or may not be implemented. Each variation of the data signalmay be preconditioned by a processor connected to the transmitter. Thetrader may pick which trading strategy to implement, and the data signalvariation corresponding to that strategy is immediately sent to areceiver at the stock exchange to execute the trade. Alternatively oradditionally, private or public news can be transmitted from the tradeor some other source to initiate a particular trading strategy.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges, equivalents, and modifications that come within the spirit ofthe inventions defined by following claims are desired to be protected.All publications, patents, and patent applications cited in thisspecification are herein incorporated by reference as if each individualpublication, patent, or patent application were specifically andindividually indicated to be incorporated by reference and set forth inits entirety herein.

Glossary of Definitions and Alternatives

The language used in the claims and specification is to only have itsplain and ordinary meaning, except as explicitly defined below. Thewords in these definitions are to only have their plain and ordinarymeaning. Such plain and ordinary meaning is inclusive of all consistentdictionary definitions from the most recently published Webster's andRandom House dictionaries. As used in the specification and claims, thefollowing definitions apply to the following terms or common variationsthereof (e.g., singular/plural forms, past/present tenses, etc.):

“Antenna” or “Antenna system” generally refers to an electrical device,or series of devices, in any suitable configuration, that convertselectric power into electromagnetic radiation. Such radiation may beeither vertically, horizontally, or circularly polarized at anyfrequency along the electromagnetic spectrum. Antennas transmitting withcircular polarity may have either right-handed or left-handedpolarization.

In the case of radio waves, an antenna may transmit at frequenciesranging along electromagnetic spectrum from extremely low frequency(ELF) to extremely high frequency (EHF). An antenna or antenna systemdesigned to transmit radio waves may comprise an arrangement of metallicconductors (elements), electrically connected (often through atransmission line) to a receiver or transmitter. An oscillating currentof electrons forced through the antenna by a transmitter can create anoscillating magnetic field around the antenna elements, while the chargeof the electrons also creates an oscillating electric field along theelements. These time-varying fields radiate away from the antenna intospace as a moving transverse electromagnetic field wave. Conversely,during reception, the oscillating electric and magnetic fields of anincoming electromagnetic wave exert force on the electrons in theantenna elements, causing them to move back and forth, creatingoscillating currents in the antenna. These currents can then be detectedby receivers and processed to retrieve digital or analog signals ordata.

Antennas can be designed to transmit and receive radio wavessubstantially equally in all horizontal directions (omnidirectionalantennas), or preferentially in a particular direction (directional orhigh gain antennas). In the latter case, an antenna may also includeadditional elements or surfaces which may or may not have any physicalelectrical connection to the transmitter or receiver. For example,parasitic elements, parabolic reflectors or horns, and other suchnon-energized elements serve to direct the radio waves into a beam orother desired radiation pattern. Thus antennas may be configured toexhibit increased or decreased directionality or “gain” by the placementof these various surfaces or elements. High gain antennas can beconfigured to direct a substantially large portion of the radiatedelectromagnetic energy in a given direction that may be verticalhorizontal or any combination thereof.

Antennas may also be configured to radiate electromagnetic energy withina specific range of vertical angles (i.e. “takeoff angles) relative tothe earth in order to focus electromagnetic energy toward an upper layerof the atmosphere such as the ionosphere. By directing electromagneticenergy toward the upper atmosphere at a specific angle, specific skipdistances may be achieved at particular times of day by transmittingelectromagnetic energy at particular frequencies.

Other examples of antennas include emitters and sensors that convertelectrical energy into pulses of electromagnetic energy in the visibleor invisible light portion of the electromagnetic spectrum. Examplesinclude light emitting diodes, lasers, and the like that are configuredto generate electromagnetic energy at frequencies ranging along theelectromagnetic spectrum from far infrared to extreme ultraviolet.

“Command” or “Command Data” generally refers to one or more directives,instructions, algorithms, or rules controlling a machine to take one ormore actions, alone or in combination. A command may be stored,transferred, transmitted, or otherwise processed in any suitable manner.For example, a command may be stored in a memory or transmitted over acommunication network as electromagnetic radiation at any suitablefrequency passing through any suitable medium.

“Computer” generally refers to any computing device configured tocompute a result from any number of input values or variables. Acomputer may include a processor for performing calculations to processinput or output. A computer may include a memory for storing values tobe processed by the processor, or for storing the results of previousprocessing.

A computer may also be configured to accept input and output from a widearray of input and output devices for receiving or sending values. Suchdevices include other computers, keyboards, mice, visual displays,printers, industrial equipment, and systems or machinery of all typesand sizes. For example, a computer can control a network interface toperform various network communications upon request. The networkinterface may be part of the computer, or characterized as separate andremote from the computer.

A computer may be a single, physical, computing device such as a desktopcomputer, a laptop computer, or may be composed of multiple devices ofthe same type such as a group of servers operating as one device in anetworked cluster, or a heterogeneous combination of different computingdevices operating as one computer and linked together by a communicationnetwork. The communication network connected to the computer may also beconnected to a wider network such as the internet. Thus computer mayinclude one or more physical processors or other computing devices orcircuitry, and may also include any suitable type of memory.

A computer may also be a virtual computing platform having an unknown orfluctuating number of physical processors and memories or memorydevices. A computer may thus be physically located in one geographicallocation or physically spread across several widely scattered locationswith multiple processors linked together by a communication network tooperate as a single computer.

The concept of “computer” and “processor” within a computer or computingdevice also encompasses any such processor or computing device servingto make calculations or comparisons as part of disclosed system.Processing operations related to threshold comparisons, rulescomparisons, calculations, and the like occurring in a computer mayoccur, for example, on separate servers, the same server with separateprocessors, or on a virtual computing environment having an unknownnumber of physical processors as described above.

A computer may be optionally coupled to one or more visual displaysand/or may include an integrated visual display. Likewise, displays maybe of the same type, or a heterogeneous combination of different visualdevices. A computer may also include one or more operator input devicessuch as a keyboard, mouse, touch screen, laser or infrared pointingdevice, or gyroscopic pointing device to name just a few representativeexamples. Also, besides a display, one or more other output devices maybe included such as a printer, plotter, industrial manufacturingmachine, 3D printer, and the like. As such, various display, input andoutput device arrangements are possible.

Multiple computers or computing devices may be configured to communicatewith one another or with other devices over wired or wirelesscommunication links to form a communication network. Networkcommunications may pass through various computers operating as networkappliances such as switches, routers, firewalls or other network devicesor interfaces before passing over other larger computer networks such asthe internet. Communications can also be passed over the communicationnetwork as wireless data transmissions carried over electromagneticwaves through transmission lines or free space. Such communicationsinclude using WiFi or other Wireless Local Area Network (WLAN) or acellular transmitter/receiver to transfer data. Such signals conform toany of a number of wireless or mobile telecommunications technologystandards such as 802.11a/b/g/n, 3G, 4G, and the like.

“Communication Link” generally refers to a connection between two ormore communicating entities and may or may not include a communicationschannel between the communicating entities. The communication betweenthe communicating entities may occur by any suitable means. For examplethe connection may be implemented as an actual physical link, anelectrical link, an electromagnetic link, a logical link, or any othersuitable linkage facilitating communication.

In the case of an actual physical link, communication may occur bymultiple components in the communication link figured to respond to oneanother by physical movement of one element in relation to another. Inthe case of an electrical link, the communication link may be composedof multiple electrical conductors electrically connected to form thecommunication link.

In the case of an electromagnetic link, elements the connection may beimplemented by sending or receiving electromagnetic energy at anysuitable frequency, thus allowing communications to pass aselectromagnetic waves. These electromagnetic waves may or may not passthrough a physical medium such as an optical fiber, or through freespace, or any combination thereof. Electromagnetic waves may be passedat any suitable frequency including any frequency in the electromagneticspectrum.

In the case of a logical link, the communication link may be aconceptual linkage between the sender and recipient such as atransmission station in the receiving station. Logical link may includeany combination of physical, electrical, electromagnetic, or other typesof communication links.

“Communication node” generally refers to a physical or logicalconnection point, redistribution point or endpoint along a communicationlink. A physical network node is generally referred to as an activeelectronic device attached or coupled to a communication link, eitherphysically, logically, or electromagnetically. A physical node iscapable of sending, receiving, or forwarding information over acommunication link. A communication node may or may not include acomputer, processor, transmitter, receiver, repeater, and/ortransmission lines, or any combination thereof.

“Computational expense” generally refers to the level of computing powerrequired to perform a particular function or calculation. A process ismore computationally expensive than another process if that processrequires greater computational resources to be completed. For example, amore computationally expensive program may require more memory or mayrequire a computer to solve more equations than a less computationallyexpensive program.

“Critical angle” generally refers to the highest angle with respect to avertical line extending to the center of the Earth at which anelectromagnetic wave at a specific frequency can be returned to theEarth using sky-wave propagation.

“Critical Frequency” generally refers to the highest frequency that willbe returned to the Earth when transmitted vertically under givenionospheric conditions using sky-wave propagation.

“Data Bandwidth” generally refers to the maximum throughput of a logicalor physical communication path in a communication system. Data bandwidthis a transfer rate that can be expressed in units of data transferredper second. In a digital communications network, the units of datatransferred are bits and the maximum throughput of a digitalcommunications network is therefore generally expressed in “bits persecond” or “bit/s.” By extension, the terms “kilobit/s” or “Kbit/s”,“Megabit/s” or “Mbit/s”, and “Gigabit/s” or “Gbit/s” can also be used toexpress the data bandwidth of a given digital communications network.Data networks may be rated according to their data bandwidth performancecharacteristics according to specific metrics such as “peak bit rate”,“mean bit rate”, “maximum sustained bit rate”, “information rate”, or“physical layer useful bit rate.” For example, bandwidth tests measurethe maximum throughput of a computer network. The reason for this usageis that according to Hartley's Law, the maximum data rate of a physicalcommunication link is proportional to its frequency bandwidth in hertz.

Data bandwidth may also be characterized according to the maximumtransfer rate for a particular communications network. For example:

“Low Data Bandwidth” generally refers to a communications network with amaximum data transfer rate that is less than or about equal to 1,000,000units of data per second. For example, in a digital communicationsnetwork, the unit of data is a bit. Therefore low data bandwidth digitalcommunications networks are networks with a maximum transfer rate thatis less than or about equal to 1,000,000 bits per second (1 Mbits/s).

“High Data Bandwidth” generally refers to a communications network witha maximum data transfer rate that is greater than about 1,000,000 unitsof data per second. For example, a digital communications network with ahigh data bandwidth is a digital communications network with a maximumtransfer rate that is greater than about 1,000,000 bits per second (1Mbits/s).

“Electromagnet Radiation” generally refers to energy radiated byelectromagnetic waves. Electromagnetic radiation is produced from othertypes of energy, and is converted to other types when it is destroyed.Electromagnetic radiation carries this energy as it travels moving awayfrom its source at the speed of light (in a vacuum). Electromagneticradiation also carries both momentum and angular momentum. Theseproperties may all be imparted to matter with which the electromagneticradiation interacts as it moves outwardly away from its source.

Electromagnetic radiation changes speed as it passes from one medium toanother. When transitioning from one media to the next, the physicalproperties of the new medium can cause some or all of the radiatedenergy to be reflected while the remaining energy passes into the newmedium. This occurs at every junction between media that electromagneticradiation encounters as it travels.

The photon is the quantum of the electromagnetic interaction, and is thebasic constituent of all forms of electromagnetic radiation. The quantumnature of light becomes more apparent at high frequencies aselectromagnetic radiation behaves more like particles and less likewaves as its frequency increases.

“Distortion” generally refers to the alteration of the original shape orother characteristic of something, and more specifically, to thealteration of the waveform of an information-bearing signal. Distortionscan include, but are not limited to, amplitude, harmonic, frequency,phase, polarization, and group delay type distortions. Distortions caninclude linear, nonlinear, systematic, and/or random changes to theinformation-bearing signal. Distortions can include changes to analogand/or digital signals.

“Electromagnetic Spectrum” generally refers to the range of all possiblefrequencies of electromagnetic radiation. The electromagnetic spectrumis generally categorized as follows, in order of increasing frequencyand energy and decreasing wavelength:

“Extremely low frequency” (ELF) generally designates a band offrequencies from about 3 to about 30 Hz with wavelengths from about100,000 to 10,000 km long.

“Super low frequency” (SLF) generally designates a band of frequenciesgenerally ranging between about 30 Hz to about 300 Hz with wavelengthsof about 10,000 to about 1000 km long.

“Voice frequency” or “voice band” generally designates electromagneticenergy that is audible to the human ear. Adult males generally speak inthe range between about 85 and about 180 Hz while adult femalesgenerally converse in the range from about 165 to about 255 Hz.

“Very low frequency” (VLF) generally designates the band of frequenciesfrom about 3 kHz to about 30 kHz with corresponding wavelengths fromabout 10 to about 100 km long.

“Low-frequency” (LF) generally designates the band of frequencies in therange of about 30 kHz to about 300 kHz with wavelengths range from about1 to about 10 km.

“Medium frequency” (MF) generally designates the band of frequenciesfrom about 300 kHz to about 3 MHz with wavelengths from about 1000 toabout 100 m long.

“High frequency” (HF) generally designates the band of frequencies fromabout 3 MHz to about 30 MHz having wavelengths from about 100 m to about10 m long.

“Very high frequency” (VHF) generally designates the band of frequenciesfrom about 30 Hz to about 300 MHz with wavelengths from about 10 m toabout 1 m long.

“Ultra high frequency” (UHF) generally designates the band offrequencies from about 300 MHz to about 3 GHz with weight wavelengthsranging from about 1 m to about 10 cm long.

“Super high frequency” (SHF) generally designates the band offrequencies from about 3 GHz to about 30 GHz with wavelengths rangingfrom about 10 cm to about 1 cm long.

“Extremely high frequency” (EHF) generally designates the band offrequencies from about 30 GHz to about 300 GHz with wavelengths rangingfrom about 1 cm to about 1 mm long.

“Far infrared” (FIR) generally designates a band of frequencies fromabout 300 GHz to about 20 THz with wavelengths ranging from about 1 mmto about 15 μm long.

“Long-wavelength infrared” (LWIR) generally designates a band offrequencies from about 20 THz to about 37 THz with wavelengths rangingfrom about 15 μm to about 8 μm long.

“Mid infrared” (MIR) generally designates a band of frequencies fromabout 37 THz to about 100 THz with wavelengths from about 8 μm to about3 μm long.

“Short wavelength infrared” (SWIR) generally designates a band offrequencies from about 100 THz to about 214 THz with wavelengths fromabout 3 μm to about 1.4 μm long

“Near-infrared” (NIR) generally designates a band of frequencies fromabout 214 THz to about 400 THz with wavelengths from about 1.4 μm toabout 750 nm long.

“Visible light” generally designates a band of frequencies from about400 THz to about 750 THz with wavelengths from about 750 nm to about 400nm long.

“Near ultraviolet” (NUV) generally designates a band of frequencies fromabout 750 THz to about 1 PHz with wavelengths from about 400 nm to about300 nm long.

“Middle ultraviolet” (MUV) generally designates a band of frequenciesfrom about 1 PHz to about 1.5 PHz with wavelengths from about 300 nm toabout 200 nm long.

“Far ultraviolet” (FUV) generally designates a band of frequencies fromabout 1.5 PHz to about 2.48 PHz with wavelengths from about 200 nm toabout 122 nm long.

“Extreme ultraviolet” (EUV) generally designates a band of frequenciesfrom about 2.48 PHz to about 30 PHz with wavelengths from about 121 nmto about 10 nm long.

“Soft x-rays” (SX) generally designates a band of frequencies from about30 PHz to about 3 EHz with wavelengths from about 10 nm to about 100 pmlong.

“Hard x-rays” (HX) generally designates a band of frequencies from about3 EHz to about 30 EHz with wavelengths from about 100 pm to about 10 pmlong.

“Gamma rays” generally designates a band of frequencies above about 30EHz with wavelengths less than about 10 pm long.

“Electromagnetic Waves” generally refers to waves having a separateelectrical and a magnetic component. The electrical and magneticcomponents of an electromagnetic wave oscillate in phase and are alwaysseparated by a 90 degree angle. Electromagnetic waves can radiate from asource to create electromagnetic radiation capable of passing through amedium or through a vacuum. Electromagnetic waves include wavesoscillating at any frequency in the electromagnetic spectrum including,but not limited to, radio waves, visible and invisible light, X-rays,and gamma-rays.

“Frequency Bandwidth” or “Band” generally refers to a contiguous rangeof frequencies defined by an upper and lower frequency. Frequencybandwidth is thus typically expressed as a number of hertz (cycles persecond) representing the difference between the upper frequency and thelower frequency of the band and may or may not include the upper andlower frequencies themselves. A “band” can therefore be defined by agiven frequency bandwidth for a given region and designated withgenerally agreed on terms. For example, the “20 meter band” in theUnited States is assigned the frequency range from 14 MHz to 14.35 MHzthus defining a frequency bandwidth of 0.35 MHz or 350 KHz. In anotherexample, the International Telecommunication Union (ITU) has designatedthe frequency range from 300 Mhz to 3 GHz as the “UHF band”.

“Fiber-optic communication” generally refers to a method of transmittingdata from one place to another by sending pulses of electromagneticenergy through an optical fiber. The transmitted energy may form anelectromagnetic carrier wave that can be modulated to carry data.Fiber-optic communication lines that use optical fiber cables totransmit data can be configured to have a high data bandwidth. Forexample, fiber-optic communication lines may have a high data bandwidthof up to about 15 Tbit/s, about 25 Tbit/s, about 100 Tbit/s, about 1Pbit/s or more. Opto-electronic repeaters may be used along afiber-optic communication line to convert the electromagnetic energyfrom one segment of fiber-optic cable into an electrical signal. Therepeater can retransmit the electrical signal as electromagnetic energyalong another segment of fiber-optic cable at a higher signal strengththan it was received.

“Financial instrument” generally refers to a tradable asset of any kind.General examples include, but are not limited to, cash, evidence of anownership interest in an entity, or a contractual right to receive ordeliver cash or another financial instrument. Specific examples includebonds, bills (e.g. commercial paper and treasury bills), stock, loans,deposits, certificates of deposit, bond futures or options on bondfutures, short-term interest rate futures, stock options, equityfutures, currency futures, interest rate swaps, interest rate caps andfloors, interest rate options, forward rate agreements, stock options,foreign-exchange options, foreign-exchange swaps, currency swaps, or anysort of derivative.

“Fused data stream” generally refers to a combination of at least two ormore separate data transmissions. The data transmissions may come fromany desired source. For example, the data transmission may be in-banddata, out-of-band data, public data, or private data. The fused datastream may be any desired combination of these different datatransmissions.

“Ground” is used more in an electrical/electromagnetic sense andgenerally refers to the Earth's surface including land and bodies ofwater, such as oceans, lakes, and rivers.

“Ground-wave propagation” generally refers to a transmission method inwhich one or more electromagnetic waves are conducted via the boundaryof the ground and atmosphere to travel along ground. The electromagneticwave propagates by interacting with the semi-conductive surface of theearth. In essence, the wave clings to the surfaces so as to follow thecurvature of the earth. Typically, but not always, the electromagneticwave is in the form of a ground or surface wave formed by low-frequencyradio waves.

“Identifier” generally refers to a name that identifies (that is, labelsthe identity of) either a unique thing or a unique class of things,where the “object” or class may be an idea, physical object (or classthereof), or physical substance (or class thereof). The abbreviation“ID” often refers to identity, identification (the process ofidentifying), or an identifier (that is, an instance of identification).An identifier may or may not include words, numbers, letters, symbols,shapes, colors, sounds, or any combination of those.

The words, numbers, letters, or symbols may follow an encoding system(wherein letters, digits, words, or symbols represent ideas or longeridentifiers) or they may simply be arbitrary. When an identifier followsan encoding system, it is often referred to as a code or ID code.Identifiers that do not follow any encoding scheme are often said to bearbitrary IDs because they are arbitrarily assigned without meaning inany other context beyond identifying something.

“In-band data” generally refers to data that is collected from the maindata transmission stream between two communication nodes. Typically,in-band data is the main data transmission sent by the transmittingparty. This data may be collected and analyzed to determine theviability of transmitting data at a certain frequency at the ionosphericconditions during the time of transmission.

“Ionosphere” generally refers to the layer of the Earth's atmospherethat contains a high concentration of ions and free electrons and isable to reflect radio waves. The ionosphere includes the thermosphere aswell as parts of the mesosphere and exosphere. The ionosphere extendsfrom about 25 to about 600 miles (about 40 to 1,000 km) above theearth's surface. The ionosphere includes a number of layers that undergoconsiderable variations in altitude, density, and thickness, dependingamong a number of factors including solar activity, such as sunspots.The various layers of the ionosphere are identified below.

The “D layer” of the ionosphere is the innermost layer that ranges fromabout 25 miles (40 km) to about 55 miles (90 km) above the Earth'ssurface. The layer has the ability to refract signals of lowfrequencies, but it allows high frequency radio signals to pass throughwith some attenuation. The D layer normally, but not in all instances,disappears rapidly after sunset due to rapid recombination of its ions.

The “E layer” of the ionosphere is the middle layer that ranges fromabout 55 miles (90 km) to about 90 miles (145 km) above the Earth'ssurface. The E layer typically has the ability to refract signals withfrequencies higher than the D layer. Depending on the conditions, the Elayer can normally refract frequencies up to 20 MHz. The rate of ionicrecombination in the E layer is somewhat rapid such that after sunset italmost completely disappears by midnight. The E layer can furtherinclude what is termed an “E_(s”)layer” or “sporadic E layer” that isformed by small, thin clouds of intense ionization. The sporadic E layercan reflect radio waves, even frequencies up to 225 MHz, althoughrarely. Sporadic E layers most often form during summer months, and ithas skip distances of around 1,020 miles (1,640 km). With the sporadic Elayer, one hop propagation can be about 560 miles (900 km) to up to1,600 miles (2,500 km), and double hop propagation can be over 2,200miles (3,500 km).

The “F layer” of the ionosphere is the top layer that ranges from about90 (145 km) to 310 miles (500 km) or more above the Earth's surface. Theionization in the F layer is typically quite high and varies widelyduring the day, with the highest ionization occurring usually aroundnoon. During daylight, the F layer separates into two layers, the F1layer and the F2 layer. The F2 layer is outermost layer and, as such, islocated higher than the F1 layer. Given the atmosphere is rarified atthese altitudes, the recombination of ions occur slowly such that Flayer remains constantly ionized, either day or night such that most(but not all) skywave propagation of radio waves occur in the F layer,thereby facilitating high frequency (HF) or short wave communicationover long distances. For example, the F layers are able to refract highfrequency, long distance transmissions for frequencies up to 30 MHz.

“Latency” generally refers to the time interval between a cause and aneffect in a system. Latency is physically a consequence of the limitedvelocity with which any physical interaction can propagate throughout asystem. Latency is physically a consequence of the limited velocity withwhich any physical interaction can propagate. The speed at which aneffect can propagate through a system is always lower than or equal tothe speed of light. Therefore every physical system that includes somedistance between the cause and the effect will experience some kind oflatency. For example, in a communication link or communications network,latency generally refers to the minimum time it takes for data to passfrom one point to another. Latency with respect to communicationsnetworks may also be characterized as the time it takes energy to movefrom one point along the network to another. With respect to delayscaused by the propagation of electromagnetic energy following aparticular propagation path, latency can be categorized as follows:

“Low Latency” generally refers to a period of time that is less than orabout equal to a propagation time that is 10% greater than the timerequired for light to travel a given propagation path in a vacuum.Expressed as a formula, low latency is defined as follows:

$\begin{matrix}{{latency}_{low} \leq {\frac{d}{c} \cdot k}} & \left( {{Equation}\mspace{14mu} 1} \right)\end{matrix}$

where:

d=distance (miles)

c=the speed of light in a vacuum (186,000 miles/sec)

k=a scalar constant of 1.1

For example, light can travel 25,000 miles through a vacuum in about0.1344 seconds. A “low latency” communication link carrying data overthis 25,000 mile propagation path would therefore be capable of passingat least some portion of the data over the link in about 0.14784 secondsor less.

“High Latency” generally refers to a period of time that is over 10%greater than the time required for light to travel a given propagationpath in a vacuum. Expressed as a formula, high latency is defined asfollows:

$\begin{matrix}{{latency}_{high} > {\frac{d}{c} \cdot k}} & \left( {{Equation}\mspace{14mu} 2} \right)\end{matrix}$

where:

d=distance (miles)

c=the speed of light in a vacuum (186,000 miles/sec)

k=a scalar constant of 1.1

For example, light can travel 8,000 miles through a vacuum in about0.04301 seconds. A “high latency” communication link carrying data overthis transmission path would therefore be capable of passing at leastsome portion of the data over the link in about 0.04731 seconds or more.

The “high” and “low” latency of a network may be independent of the databandwidth. Some “high” latency networks may have a high transfer ratethat is higher than a “low” latency network, but this may not always bethe case. Some “low” latency networks may have a data bandwidth thatexceeds the bandwidth of a “high” latency network.

“Maximum Usable Frequency (MUF)” generally refers to the highestfrequency that is returned to the Earth using sky-wave propagation.

“Memory” generally refers to any storage system or device configured toretain data or information. Each memory may include one or more types ofsolid-state electronic memory, magnetic memory, or optical memory, justto name a few. By way of non-limiting example, each memory may includesolid-state electronic Random Access Memory (RAM), SequentiallyAccessible Memory (SAM) (such as the First-In, First-Out (FIFO) varietyor the Last-In-First-Out (LIFO) variety), Programmable Read Only Memory(PROM), Electronically Programmable Read Only Memory (EPROM), orElectrically Erasable Programmable Read Only Memory (EEPROM); an opticaldisc memory (such as a DVD or CD ROM); a magnetically encoded hard disc,floppy disc, tape, or cartridge media; or a combination of any of thesememory types. Also, each memory may be volatile, nonvolatile, or ahybrid combination of volatile and nonvolatile varieties.

“Noise” generally refers to one or more disturbances that interfere withand/or prevent reception of a signal and/or information.

“Non-sky-wave propagation” generally refers to all forms oftransmission, wired and/or wireless, in which the information is nottransmitted by reflecting an electromagnetic wave from the ionosphere.

“Optimum Working Frequency” generally refers to the frequency thatprovides the most consistent communication path via sky-wavepropagation. It can vary over time depending on number of factors, suchas ionospheric conditions and time of day. For transmissions using theF2 layer of the ionosphere the working frequency is generally around 85%of the MUF, and for the E layer, the optimum working frequency willgenerally be near the MUF.

“Optical Fiber” generally refers to an electromagnetic waveguide havingan elongate conduit that includes a substantially transparent mediumthrough which electromagnetic energy travels as it traverses the longaxis of the conduit. Electromagnetic radiation may be maintained withinthe conduit by total internal reflection of the electromagneticradiation as it traverses the conduit. Total internal reflection isgenerally achieved using optical fibers that include a substantiallytransparent core surrounded by a second substantially transparentcladding material with a lower index of refraction than the core.

Optical fibers are generally constructed of dielectric material that isnot electrically conductive but is substantially transparent. Suchmaterials may or may not include any combination of extruded glass suchas silica, fluoride glass, phosphate glass, Chalcogenide glass, orpolymeric material such as various types of plastic, or other suitablematerial and may be configured with any suitable cross-sectional shape,length, or dimension. Examples of electromagnetic energy that may besuccessfully passed through optical fibers include electromagnetic wavesin the near-infrared, mid-infrared, and visible light portion of theelectromagnetic spectrum, although electromagnetic energy of anysuitable frequency may be used.

“Out-of-band data” generally refers to data that is collected from achannel that is independent of the channel through which the main datastream is transmitted. The out-of-band data may be data streams sent byskywave propagation by third parties or may be data streams sent by thetransmitting party along a different channel than the main datatransmission stream. The data collected may include ionospheric data,for example from an ionosonde, or may be general data that is collectedand analyzed to determine the viability of transmitting data at acertain frequency at the current ionospheric conditions.

“Polarization” generally refers to the orientation of the electric field(“E-plane”) of a radiated electromagnetic energy wave with respect tothe Earth's surface and is determined by the physical structure andorientation of the radiating antenna. Polarization can be consideredseparately from an antenna's directionality. Thus, a simple straightwire antenna may have one polarization when mounted abstention thevertically, and a different polarization when mounted substantiallyhorizontally. As a transverse wave, the magnetic field of a radio waveis at right angles to that of the electric field, but by convention,talk of an antenna's “polarization” is understood to refer to thedirection of the electric field.

Reflections generally affect polarization. For radio waves, oneimportant reflector is the ionosphere which can change the wave'spolarization. Thus for signals received via reflection by the ionosphere(a skywave), a consistent polarization cannot be expected. Forline-of-sight communications or ground wave propagation, horizontally orvertically polarized transmissions generally remain in about the samepolarization state at the receiving location. Matching the receivingantenna's polarization to that of the transmitter may be especiallyimportant in ground wave or line of sight propagation but may be lessimportant in skywave propagation.

An antenna's linear polarization is generally along the direction (asviewed from the receiving location) of the antenna's currents when sucha direction can be defined. For instance, a vertical whip antenna orWi-Fi antenna vertically oriented will transmit and receive in thevertical polarization. Antennas with horizontal elements, such as mostrooftop TV antennas, are generally horizontally polarized (becausebroadcast TV usually uses horizontal polarization). Even when theantenna system has a vertical orientation, such as an array ofhorizontal dipole antennas, the polarization is in the horizontaldirection corresponding to the current flow.

Polarization is the sum of the E-plane orientations over time projectedonto an imaginary plane perpendicular to the direction of motion of theradio wave. In the most general case, polarization is elliptical,meaning that the polarization of the radio waves varies over time. Twospecial cases are linear polarization (the ellipse collapses into aline) as we have discussed above, and circular polarization (in whichthe two axes of the ellipse are equal). In linear polarization theelectric field of the radio wave oscillates back and forth along onedirection; this can be affected by the mounting of the antenna butusually the desired direction is either horizontal or verticalpolarization. In circular polarization, the electric field (and magneticfield) of the radio wave rotates At the radio frequency circularlyaround the axis of propagation.

“Precondition” generally refers to the alteration of a waveform of aninformation-bearing signal before and/or during transmission so thatdistortions in the received waveform are reduced and/or eliminated. Inone non-limiting example, an inverse function of the measured and/orpredicted distortion is applied to the transmitted signal so as tocorrect for distortions. Some alterations to precondition the signal caninclude changes to amplitude, harmonics, frequency, phase, and/orpolarization of the waveform, to name just a few examples. Thesealterations can include linear, nonlinear, systematic, and/or randomcharacteristics. Precondition alterations can include analog and/ordigital changes.

“Private data” generally refers to ionospheric data that is collectedfrom sources that are not available to the general public. Private datamay be historical or current ionospheric data collected by the partythat is performing data transmission, or may be ionospheric data that ispurchased from a third party by the party that is performing datatransmission. Private data may also be high frequency data transmissionssent by skywave propagation that may be collected and analyzed fortransmission properties, such as distortion, that may indicate theviability of a certain transmission frequency.

“Processor” generally refers to one or more electronic componentsconfigured to operate as a single unit configured or programmed toprocess input to generate an output. Alternatively, when of amulti-component form, a processor may have one or more componentslocated remotely relative to the others. One or more components of eachprocessor may be of the electronic variety defining digital circuitry,analog circuitry, or both. In one example, each processor is of aconventional, integrated circuit microprocessor arrangement, such as oneor more PENTIUM, i3, i5 or i7 processors supplied by INTEL Corporationof 2200 Mission College Boulevard, Santa Clara, Calif. 95052, USA.

Another example of a processor is an Application-Specific IntegratedCircuit (ASIC). An ASIC is an Integrated Circuit (IC) customized toperform a specific series of logical operations is controlling thecomputer to perform specific tasks or functions. An ASIC is an exampleof a processor for a special purpose computer, rather than a processorconfigured for general-purpose use. An application-specific integratedcircuit generally is not reprogrammable to perform other functions andmay be programmed once when it is manufactured.

In another example, a processor may be of the “field programmable” type.Such processors may be programmed multiple times “in the field” toperform various specialized or general functions after they aremanufactured. A field-programmable processor may include aField-Programmable Gate Array (FPGA) in an integrated circuit in theprocessor. FPGA may be programmed to perform a specific series ofinstructions which may be retained in nonvolatile memory cells in theFPGA. The FPGA may be configured by a customer or a designer using ahardware description language (HDL). In FPGA may be reprogrammed usinganother computer to reconfigure the FPGA to implement a new set ofcommands or operating instructions. Such an operation may be executed inany suitable means such as by a firmware upgrade to the processorcircuitry.

Just as the concept of a computer is not limited to a single physicaldevice in a single location, so also the concept of a “processor” is notlimited to a single physical logic circuit or package of circuits butincludes one or more such circuits or circuit packages possiblycontained within or across multiple computers in numerous physicallocations. In a virtual computing environment, an unknown number ofphysical processors may be actively processing data, the unknown numbermay automatically change over time as well.

The concept of a “processor” includes a device configured or programmedto make threshold comparisons, rules comparisons, calculations, orperform logical operations applying a rule to data yielding a logicalresult (e.g. “true” or “false”). Processing activities may occur inmultiple single processors on separate servers, on multiple processorsin a single server with separate processors, or on multiple processorsphysically remote from one another in separate computing devices.

“Public data” generally refers to ionospheric data that is freelyavailable to the public or any interested party. Public data may beionosonde data collected and made available by governmental agenciessuch as NASA, the National Oceanic and Atmospheric Administration(NOAA), or any other public entity that collects and distributesionospheric data. Public data may be historic data or real-time data.Public data may also be high frequency data transmissions sent byskywave propagation that may be collected and analyzed for transmissionproperties, such as distortion, that may indicate the viability of acertain transmission frequency.

“Radio” generally refers to electromagnetic radiation in the frequenciesthat occupy the range from 3 kHz to 300 GHz.

“Radio horizon” generally refers the locus of points at which directrays from an antenna are tangential to the ground. The radio horizon canbe approximated by the following equation:

d≅√{square root over (2h _(t))}+√{square root over (2h _(r))}  (Equation3)

where:

d=radio horizon (miles)

h_(t)=transmitting antenna height (feet)

h_(r)=receiving antenna height (feet).

“Remote” generally refers to any physical, logical, or other separationbetween two things. The separation may be relatively large, such asthousands or millions of miles or kilometers, or small such asnanometers or millionths of an inch. Two things “remote” from oneanother may also be logically or physically coupled or connectedtogether.

“Receive” generally refers to accepting something transferred,communicated, conveyed, relayed, dispatched, or forwarded. The conceptmay or may not include the act of listening or waiting for something toarrive from a transmitting entity. For example, a transmission may bereceived without knowledge as to who or what transmitted it. Likewisethe transmission may be sent with or without knowledge of who or what isreceiving it. To “receive” may include, but is not limited to, the actof capturing or obtaining electromagnetic energy at any suitablefrequency in the electromagnetic spectrum. Receiving may occur bysensing electromagnetic radiation. Sensing electromagnetic radiation mayinvolve detecting energy waves moving through or from a medium such as awire or optical fiber. Receiving includes receiving digital signalswhich may define various types of analog or binary data such as signals,datagrams, packets and the like.

“Receiving Station” generally refers to a receiving device, or to alocation facility having multiple devices configured to receiveelectromagnetic energy. A receiving station may be configured to receivefrom a particular transmitting entity, or from any transmitting entityregardless of whether the transmitting entity is identifiable in advanceof receiving the transmission.

“Reflection point” generally refers to the location in the ionosphere atwhich a radio wave is refracted by the ionosphere so that it begins totravel back to the surface of the earth rather than further into theatmosphere.

“Sensor” generally refers to any device that detects or measures aphysical property. The physical property that is measured may be anatmospheric condition, but this is not required. For example, a sensormay measure atmospheric conditions, such as ionospheric height. A sensormay also collect data related to temperature, wind speed, lightning, orany of a number of other weather related parameters. A sensor may belimited to the measurement of a single physical property or may becapable of measuring several different physical properties.

“Skip distance” generally refers to the minimum distance from atransmitter to where a wave from sky-wave propagation can be returned tothe Earth. To put it another way, the skip distance is the minimumdistance that occurs at the critical angle for sky-wave propagation.

“Skip zone” or “quiet zone” generally refers to is an area between thelocation where a ground wave from ground wave propagation is completelydissipated and the location where the first sky wave returns using skywave propagation. In the skip zone, no signal for a given transmissioncan be received.

“Satellite communication” or “satellite propagation” generally refers totransmitting one or more electromagnetic signals to a satellite which inturn reflects and/or retransmits the signal to another satellite orstation.

“Size” generally refers to the extent of something; a thing's overalldimensions or magnitude; how big something is. For physical objects,size may be used to describe relative terms such as large or larger,high or higher, low or lower, small or smaller, and the like. Size ofphysical objects may also be given in fixed units such as a specificwidth, length, height, distance, volume, and the like expressed in anysuitable units.

For data transfer, size may be used to indicate a relative or fixedquantity of data being manipulated, addressed, transmitted, received, orprocessed as a logical or physical unit. Size may be used in conjunctionwith the amount of data in a data collection, data set, data file, orother such logical unit. For example, a data collection or data file maybe characterized as having a “size” of 35 Mbytes, or a communicationlink may be characterized as having a data bandwidth with a “size” of1000 bits per second.

“Sky-wave propagation” refers generally to a transmission method inwhich one or more electromagnetic-waves radiated from an antenna arerefracted from the ionosphere back to the ground. Sky-wave propagationfurther includes tropospheric scatter transmissions. In one form, askipping method can be used in which the waves refracted from theionosphere are reflected by the ground back up to the ionosphere. Thisskipping can occur more than once.

“Space-wave propagation” or sometimes referred to as “direct wavepropagation” or “line-of-sight propagation” generally refers to atransmission method in which one or more electromagnetic waves aretransmitted between antennas that are generally visible to one another.The transmission can occur via direct and/or ground reflected spacewaves. Generally speaking, the antenna height and curvature of the earthare limiting factors for the transmission distances for space-wavepropagation. The actual radio horizon for a direct line of sight islarger than the visible or geometric line of sight due to diffractioneffects; that is, the radio horizon is about ⅘ greater than thegeometric line of sight.

“Spread spectrum” generally refers to a transmission method thatincludes sending a portion of a transmitted signal over multiplefrequencies. The transmission over multiple frequencies may occursimultaneously by sending a portion of the signal on variousfrequencies. In this example, a receiver must listen to all frequenciessimultaneously in order to reassemble the transmitted signal. Thetransmission may also be spread over multiple frequencies by “hopping”signals. A signal hopping scenario includes transmitting the signal forsome period of time over a first frequency, switching to transmit thesignal over a second frequency for a second period of time, beforeswitching to a third frequency for a third period of time, and so forth.The receiver and transmitter must be synchronized in order to switchfrequencies together. This process of “hopping” frequencies may beimplemented in a frequency-hopping pattern that may change over time(e.g. every hour, every 24 hours, and the like).

“Stratosphere” generally refers to a layer of the Earth's atmosphereextending from the troposphere to about 25 to 35 miles above the earthsurface.

“Transfer Rate” generally refers to the rate at which a something ismoved from one physical or logical location to another. In the case of acommunication link or communication network, a transfer rate may becharacterized as the rate of data transfer over the link or network.Such a transfer rate may be expressed in “bits per second” and may belimited by the maximum data bandwidth for a given network orcommunication link used to carry out a transfer of data.

“Transmission frequency model” generally refers to a method ofdetermining a suitable frequency for data transmission along aconsistent communication path via skywave propagation. The transmissionfrequency model may be used to determine a suitable frequency fortransmission in real time and/or may be used to predict future suitablefrequencies as well as when to switch frequency of data transmission. Atransmission frequency model may accept various types of data as aninput, for example transmitted data streams, environmental data,historical data, and any other desired types of data for determining atransmission frequency. In some instances, a transmission frequencymodel may be a computer program and stored in computer memory andoperable using a computer processor.

“Transmission line” generally refers to a specialized physical structureor series of structures designed to carry electromagnetic energy fromone location to another, usually without radiating the electromagneticenergy through free space. A transmission line operates to retain andtransfer electromagnetic energy from one location to another whileminimizing latency and power losses incurred as the electromagneticenergy passes through the structures in the transmission line.

Examples of transmission lines that may be used in communicating radiowaves include twin lead, coaxial cable, microstrip, strip line,twisted-pair, star quad, lecher lines, various types of waveguide, or asimple single wire line. Other types of transmission lines such asoptical fibers may be used for carrying higher frequency electromagneticradiation such as visible or invisible light.

“Transmission Path” or “Propagation Path” generally refers to path takenby electromagnetic energy passing through space or through a medium.This can include transmissions through a transmission line. In thiscase, the transmission path is defined by, follows, is contained within,passes through, or generally includes the transmission line. Atransmission or propagation path need not be defined by a transmissionline. A propagation or transmission path can be defined byelectromagnetic energy moving through free space or through theatmosphere such as in skywave, ground wave, line-of-site, or other formsof propagation. In that case, the transmission path can be characterizedas any path along which the electromagnetic energy passes as it is movesfrom the transmitter to the receiver, including any skip, bounce,scatter, or other variations in the direction of the transmitted energy.

“Transmission Station” generally refers to a transmitting device, or toa location or facility having multiple devices configured to transmitelectromagnetic energy. A transmission station may be configured totransmit to a particular receiving entity, to any entity configured toreceive transmission, or any combination thereof.

“Transmit” generally refers to causing something to be transferred,communicated, conveyed, relayed, dispatched, or forwarded. The conceptmay or may not include the act of conveying something from atransmitting entity to a receiving entity. For example, a transmissionmay be received without knowledge as to who or what transmitted it.Likewise the transmission may be sent with or without knowledge of whoor what is receiving it. To “transmit” may include, but is not limitedto, the act of sending or broadcasting electromagnetic energy at anysuitable frequency in the electromagnetic spectrum. Transmissions mayinclude digital signals which may define various types of binary datasuch as datagrams, packets and the like. A transmission may also includeanalog signals.

“Triggering Data” generally refers to data that includes triggeringinformation identifying one or more commands to execute. The triggeringdata and the command data may occur together in a single transmission ormay be transmitted separately along a single or multiple communicationlinks.

“Troposphere” generally refers to the lowest portion of the Earth'satmosphere. The troposphere extends about 11 miles above the surface ofthe earth in the mid-latitudes, up to 12 miles in the tropics, and about4.3 miles in winter at the poles.

“Tropospheric scatter transmission” generally refers to a form ofsky-wave propagation in which one or more electromagnetic waves, such asradio waves, are aimed at the troposphere. While not certain as to itscause, a small amount of energy of the waves is scattered forwards to areceiving antenna. Due to severe fading problems, diversity receptiontechniques (e.g., space, frequency, and/or angle diversity) aretypically used.

“Wave Guide” generally refers to a transmission line configured toguides waves such as electromagnetic waves occurring at any frequencyalong the electromagnetic spectrum. Examples include any arrangement ofconductive or insulative material configured to transfer lower frequencyelectromagnetic radiation ranging along the electromagnetic spectrumfrom extremely low frequency to extremely high frequency waves. Othersspecific examples include optical fibers guiding high-frequency light orhollow conductive metal pipe used to carry high-frequency radio waves,particularly microwaves.

It should be noted that the singular forms “a”, “an”, “the”, and thelike as used in the description and/or the claims include the pluralforms unless expressly discussed otherwise. For example, if thespecification and/or claims refer to “a device” or “the device”, itincludes one or more of such devices.

It should be noted that directional terms, such as “up”, “down”, “top”“bottom”, “fore”, “aft”, “lateral”, “longitudinal”, “radial”,“circumferential”, etc., are used herein solely for the convenience ofthe reader in order to aid in the reader's understanding of theillustrated embodiments, and it is not the intent that the use of thesedirectional terms in any manner limit the described, illustrated, and/orclaimed features to a specific direction and/or orientation.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges, equivalents, and modifications that come within the spirit ofthe inventions defined by following claims are desired to be protected.All publications, patents, and patent applications cited in thisspecification are herein incorporated by reference as if each individualpublication, patent, or patent application were specifically andindividually indicated to be incorporated by reference and set forth inits entirety herein.

What is claimed is:
 1. A system comprising: a first communication nodeconfigured to transmit a first data signal as an electromagnetic wavealong a first data transmission path using skywave propagation and totransmit a second data signal along a second data transmission path;wherein the first data signal is identical to second data signal; asecond communication node configured to receive the first data signaland the second data signal transmitted from the first communicationnode, and wherein the second communication node includes a processorconfigured to decode and compare the first data signal to the seconddata signal received at the second communication node; whereindifferences between the first data signal and the second data signalreceived at the second communication node indicate distortion caused byskywave propagation; and, wherein the distortions in the first datasignal are communicated to the first communication node so that a thirddata signal transmitted by the first communication node ispreconditioned to correspond with the distortion caused by skywavepropagation.
 2. The system of claim 1, wherein the second datatransmission path is a wired transmission line from the firstcommunication node the second communication node.
 3. The system of claim1, wherein the second data transmission path includes a fiber opticcable.
 4. The system of claim 1, wherein the first and second datasignals are decoded using at least two different decoding methods, andwherein the decoded signal resulting from the decoding method that takesthe shortest time is processed.
 5. The system of claim 4, wherein the atleast two decoding methods are performed in parallel.
 6. The system ofclaim 4, wherein the at least two decoding methods are performedsequentially.
 7. The system of claim 1, wherein the distortions in thefirst data signal are communicated to the first communication node bythe second data transmission path.
 8. A method comprising: sending afirst data signal from a transmitter to a receiver by a first datatransmission path using skywave propagation; sending a second datasignal from the transmitter to the receiver by a second datatransmission path; wherein the second data signal is identical to thefirst data signal; decoding the received first data signal and thereceived second data signal at the receiver; comparing the receivedfirst data signal to the received second data signal, whereindifferences between the received first data signal and the receivedsecond data signal indicate distortions caused during the skywavepropagation of the first data signal; transmitting data regarding thedistortions in the received first data signal from the receiver to thetransmitter; and, preconditioning a third data signal; wherein thepreconditioning of the third data signal corresponds to the distortionsin the received first data signal.
 9. The method of claim 8, furthercomprising: sending the preconditioned third data signal from atransmitter to a receiver by skywave propagation.
 10. The method ofclaim 8, wherein the received first data signal is decoded using atleast two different decoding methods, and wherein the decoded signalresulting from the decoding method that takes the shortest time isprocessed.
 11. The method of claim 10, wherein the at least two decodingmethods are performed in parallel.
 12. The method of claim 10, whereinthe at least two decoding methods are performed sequentially.
 13. Themethod of claim 8, wherein the second data transmission path is a wiredtransmission line from the first communication node to the secondcommunication node.
 14. The method of claim 8, wherein the second datatransmission path includes a fiber optic cable.
 15. The method of claim8, wherein the data regarding the distortions in the first data signalare transmitted from the receiver to the transmitter by the second datatransmission path.
 16. The method of claim 8, wherein the data regardingthe distortions in the first data signal are transmitted from thereceiver to the transmitter by both the first data transmission path andthe second data transmission path.
 17. A method comprising: transmittinga preconditioned data signal from a first communication node usingskywave propagation; receiving the preconditioned data signal at asecond communication node; performing a first decoding method on thedata signal; performing a second decoding method on the data signal atthe same time as the first decoding method; processing the data signalresulting from the decoding method that is quickest to decode the datasignal.
 18. The method of claim 17, wherein the second decoding methodis more computationally expensive than the first decoding method. 19.The method of claim 17, further comprising: performing a third decodingmethod on the data signal at the same time as the first and seconddecoding methods.
 20. The method of claim 19, wherein the third decodingmethod is more computationally expensive than both the first decodingmethod and the second decoding method.